Thermally Driven Supramolecular Chirality Evolution in Low-Bandgap Fused-Ring Conjugated Molecules for...

Near-infrared (NIR) circularly polarized light (CPL) photodetection is of great importance due to its broad application potential in bioimaging, wearable healthcare, optical communication, and advanced optoelectronic systems. In this study, a supramolecular chirality evolution strategy in chiral low-bandgap fused-ring conjugated molecules (LFCs) is presented for high-performance NIR CPL photodetection using Schottky barrier vertical organic field-effect transistors (SB-VOFETs). Halogen substitution combined with thermal annealing drives inversion and amplification of supramolecular chirality in enantiopure LFC thin films. F-substituted LFCs exhibit progressive domain growth and hierarchical ordering with increasing annealing temperature, whereas Cl-substituted LFCs show limited structural evolution above 150°C. These distinct crystallization behaviors directly correlate with chiroptical responses, with F-substituted LFCs achieving a maximum absorption dissymmetry factor (|g_abs|) of ∼0.1. When integrated into SB-VOFETs, the optimized chiral films enable highly efficient NIR CPL photodetection, delivering a photocurrent dissymmetry factor (|g_ph|) of ∼0.1, a specific detectivity of 4.9 × 10^{1 1} Jones, an external quantum efficiency exceeding 900%, and a fast response time of ∼600 µs at 850 nm. These metrics represent the highest performance reported for NIR CPL. This study provides design guidelines for advancing high-performance chiral optoelectronic devices through the synergistic integration of atomic substitution, thermal annealing, and device architecture engineering.